The step by running from branch to branch pretty much works with this checkin (at least for x86_64) but is still
turned off, it needs more qualification.  If you want to play with it, change the initialization of m_use_fast_step
to true.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@176923 91177308-0d34-0410-b5e6-96231b3b80d8